In recent years, visible light communication (VLC) technologies have developed at a growing pace and evolved as rising wireless communications technologies. VLC is a communication manner in which an electromagnetic wave within a range of a visible light frequency band is used as a transmission medium for communication. A principle of the VLC is implementing signal transmission by changing intensity of a light emitting diode (LED) light source. As light intensity changes at relatively high frequency, human eyes cannot discover a light source change. Therefore, a communication function can be implemented while a basic illumination function is implemented. Compared with a conventional wireless communications technology, the VLC technologies have many advantages such as a wide available spectrum, no electromagnetic interference, widely distributed infrastructures, being safe to human body, and high confidentiality. Therefore, in recent years, the VLC technologies have been attached with importance in academia and in industry and have entered a rapid development period.
In the prior art, one VLC network is referred to as a visible light communication personal area network (VPAN). FIG. 1 shows a VPAN in a star topology. The VPAN includes a coordinator and a plurality of VLC devices. The coordinator is a master node (usually acted by an LED light on a ceiling) on the VPAN, being responsible for establishing and managing the VPAN and providing network access for the VLC devices (usually acted by various consumer electronics integrated with a VLC transceiver, such as a smartphone, a tablet computer, or a PC). The VLC devices access, by using visible light as a transmission carrier and by using the coordinator, the VPAN for communication.
According to the IEEE 802.15.7 standard, a coordinator needs to perform active scanning before establishing a new VPAN as well as after detecting a VPAN identifier (VPAN ID) conflict event. An objective of active VPAN scanning is to receive, as more as possible, a beacon broadcast by a coordinator of another VPAN, so as to learn information about the another VPAN. Certainly, this information includes VPAN ID information of the another VPAN. The coordinator needs to select, for the VPAN, a VPAN ID different from that of the another VPAN after active scanning ends, so as to avoid a VPAN ID conflict.
However, according to a light intensity distribution calculation formula of the Lambertian radiation model, it can be learned that a probability that LED lights deployed on ceilings on a same horizontal plane correctly receive a signal of another LED light is extremely low; therefore, a probability that a coordinator successfully receives a beacon from another coordinator is also extremely low. Therefore, a prior-art method in which a coordinator on a VPAN network receives a beacon needs to be advanced.